This invention relates to pressure and force sensing devices and to transducers for generating electrical signals corresponding to sensed pressure and force values.
A great many devices are known for sensing force and pressure values. (For the purpose of the present discussion, the terms force and pressure can be considered interchangeable, and to include other force related values such as torque). Many are mechanical in nature, and many are electrical devices. While many of these devices have proven very effective for their intended uses, there remains a need in many areas for compact, reliable, effective and inexpensive pressure sensor and transducer devices. For example, in U.S. patent application Ser. No. 834,609 (now abandoned) filed on even date herewith and entitled "Warning Systems for Excessive Orthopedic Pressures", a non-invasive system for monitoring the pressure beneath the cast on a part of the body is disclosed for warning when the measured pressure is approaching dangerous levels. That system should incorporate sensor and transducer devices which are compact enough to fit beneath the cast without requiring any modification to the cast's size or shape, reliable and effective to protect the patient, and inexpensive. Although means are known for measuring pressures beneath casts, among the reasons why such means are not widely used is their prohobitive cost, particularly in view of the present absence of such systems in present orthopedic procedures and the view that the addition of such systems would increase the cost of the cast.
Other applications for pressure monitoring systems which might well be fulfilled upon the availability of compact, reliable, effective and inexpensive pressure sensors and transducers are in the fields of athletics (measuring force applied to boxing gloves, boxing bags and running shoes; measuring total energy expended bicycling; monitoring pressure in ski bindings and ski boots; measuring muscular expansion in weight lifters), weight measurement, pneumatic tire pressure measurement, etc.